I use an hdpe tube (used for ice-makers or some such) and drilled the
smallest possible holes (.024 - about .6 mm). by trial and error I
found that if I space the holes closer together towards the sealed end
of the tube, I was able to get fairly uniform bubble distribution. I
heated up the tube first with a torch and bent it to shape - kind of a
"J" when the bottom is almost as wide as the tank. This took multiple
trials as overheating hdpe is not a good thing :). In the end, I got
something that is butt-ugly but works well enough. The bubbles aren't
small but I get very even etches.
--- In
Homebrew_PCBs@yahoogroups.com, Adam Seychell <a_seychell@y...>
wrote:
> Does anyone know if those flexible air bubble hoses used for fish tanks
> are any good for ferric or CuCl etch tanks ?
>
> see, http://store1.yimg.com/I/animalworldnetwork_1863_24150004
>
> I know they have a lead metal insert that gives them ability to be
> shaped, and provides the weight. If this lead is not covered in plastic
> then it will not stand up to these etchants after a while. I've just
> ordered some to try, as I'm having bad luck with other "air stones"
sold
> at aquarium stores.
>
> I've tried garden "soaker" hose, but the consistency of air release is
> very poor across its length. Its not designed for fish tanks.
>
> I've also tried a series of 1mm holes in PVC tube, but the air bubbles
> are too large causing very low back pressure. Again this gives very
> non-uniform bubbling across its length. I found the air volume
needed to
> get good back pressure way too high (tested with water tank and a
> compressor).
>
> So I've come to conclusion you need lots of evenly distributed small
> bubbles to get uniform agitation.